Climate and environmental issues is now high on the agenda. We live in a generation that must try to solve some major environmental problems. Buildings and habitations account for approximately 40 % of Sweden's total energy today. To reduce this figure, as needed, more research in the field of energy efficiency is required.This thesis concerns the heating of buildings. The load on district heating is heavy during certain times of the day.

The purpose of this degree project was to build laboratory equipment for a new course in power electronics that starts this autumn 2010 at Uppsala University. The equipment is intended for student labs and it covers the most important areas of the course including rectifying, buck-/boost-converters and PWM-modulation. It is built as one sealed unit where all the electronics are built-in but visible and it has a connection board where students safely can connect the different circuits. The project has advanced from theoretical studies of circuit design, choosing of components and simulations to drawing the printed circuit board (PCB), soldering, case building, final testing and troubleshooting - basically most steps from an early idea to a final product. Measurements on the final product gave about the same results as the earlier simulations of the circuits and the result is overall satisfying..

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

Climate and environmental issues is now high on the agenda. We live in a generation that must try to solve some major environmental problems. Buildings and habitations account for approximately 40 % of Sweden's total energy today. To reduce this figure, as needed, more research in the field of energy efficiency is required.This thesis concerns the heating of buildings. The load on district heating is heavy during certain times of the day.

The competitive nature of the automotive industry has always implied a necessity to improve product development concerning time-to-market, cost and product quality. As capacity of computer-aided engineering (CAE) tools has evolved, so has the strive for simulation-driven design. Virtual durability testing using full vehicle models is one of many challenges posed in front of vehicle manufacturers when computer simulations are given a key role in product development.This thesis has been initiated as a preliminary step towards implementing dynamic virtual durability testing in the development of buses and coaches at Scania. The objective has been to assess the predictability of a full vehicle coach model and to what level of precision structural loads can be predicted. Previously performed proving ground testing of a Scania Touring coach has been the basis for the modelling and simulations in this thesis.A virtual model of the Scania Touring coach has been created in multi-body simulation software package MSC.Adams.

The government regulations for energy use in buildings will be tightened in the future. At the same time the interest in environmental classifications and certifications of buildings is increasing. This has meant a new situation for solar energy. The designs of solar heating systems are often based on experience and/or rules of thumb, rather than calculations and simulations. This thesis examines whether simulation tools, in this case Polysun, are useful in this work.

ABB is one of the world?s leading engineering companies in power and automation technologiesand their solutions improve performance while lowering environmental impacts for energycompanies and industries. ABB FACTS designs equipment and plants for series and phasecompensation.This thesis has been performed at ABB FACTS on the Mechanical Design (DM) department inVästerås, Sweden. The purpose of the thesis was to develop and design calculations andsimulation tools for ABB FACTS?s standard series capacitor platforms.

When driving hard and cornering on a circuit good control of a car?s roll is desired, so the car reaches steady state quickly but yet in a controlled fashion. This control is mainly given by the combination of the cars springs, shock absorbers and anti-roll bars.The aim of this report is to investigate, analyze and measure a Porsche Boxster?s turn in behaviour and roll dynamics as well as with the aid of simulation results give suggestions for improvement of the previous mentioned combination.Two different simulations were made, one based on a simpler model that was based on an evolved version of the bicycle model in Matlab and one was more advanced model in the simulation software rFactor. Measurements of the real car was made using a GPS-based measurement system.

The government regulations for energy use in buildings will be tightened in the future. At the same time the interest in environmental classifications and certifications of buildings is increasing. This has meant a new situation for solar energy. The designs of solar heating systems are often based on experience and/or rules of thumb, rather than calculations and simulations. This thesis examines whether simulation tools, in this case Polysun, are useful in this work.

The aim of this essay was to study the nitrogen flow in two willowplantations, at different locations in the south of Sweden, that wereirrigated with sewage. The study was also performed to compare thedifferences in nitrogen flows between two years, 1998 and 1999. The studywas made in three parts. First, the denitrification activity was measuredusing the acetylen inhibition method. Second the nitrogen flow, as well asthe water- and heat flows, were modeled through the SOIL-SOILN-modelThird; the nitrogen flow was calculated to compare with the results fromthe model.The results from the measurements were then compared with the resultsfrom the SOILN-simulations to detect differences in the denitrificationrate.

This thesis work contains a litterature study about electrical motors in general and how PWM-patterns for brushless DC-motors can be made. A suitable method has been implemented as a simulation model in VHDL. A simulation model of a brushless DC-motor which describes the phasecurrents, torque and angular velocity has also been made. The motor model made simulations easier for the complete PWM-system. The design was synthesised and tested with a prototypeboard including a SPARTAN II FPGA.

Stands where pre commercial thinning has been ignored or inadequate often tend to have high stem density and low average diameter when they reach heights of thinning. In such stands, it can often be expensive to do a conventional pulpwood harvest as a first thinning. This study investigates the development of the stands and the economic outcome of forest fuel extraction, or a combined harvest as alternatives to the ordinary pulpwood harvest. Simulations in Heureka StandWise were performed for two thin and dense stands, which were constructed by data from the Swedish National Forest Inventory. The simulations show that the extraction of forest fuel in first thinning at an early stage can provide higher net revenue compared to conventional pulpwood harvest at the same time or later.

When models are used to describe physical phenomenon during development or modification of a technical system, it is often possible to reduce both the time needed and the overall development cost. With the use of models it is also possible to investigate the potential of the selected solution, without the need for any expensive details and testrigs. In many cases it is also not possible to test all the aspects regarding the functionality that are desired from the system, without using the complete and final product.In this case a model based approach has been used to optimize the different parameters in the new snubbing mechanism for the Nose Landing Gear Retract Actuator on the JAS39 Gripen.During the simulations, upper and lower boundaries were calculated for the length of the spring and the diameter for the restrictor. The governing constraints were given by the requirements for the retraction time during cold conditions and that the amplitude of the alternating loads in the uplock mechanism were brought to an acceptable level.The most promising results from the simulations were then used in a limited number of trials in the hydraulic rig to verify that the configurations comply with the requirements.The final parameters for the snubbing mechanism were chosen to 35±1mm for the spring and 0.4-0.5 mm diameter for the restrictor..

This master thesis is a study on how a rategyro triad, an accelerometer triad, and a magnetometer triad can be integrated into a navigation system, estimating a vehicle?s attitude, i.e. its roll, tipp, and heading angles. When only a rategyro triad is used to estimate a vehicle?s attitude, a drift in the attitude occurs due to sensor errors.

The aim of this project was to develop a numerical model simulating the global transport of air pollution. The model currently used by SMHI, the Swedish Meteorological and Hydrological Institute, was intended to perform such simulations at regional scales. However, the usage of a grid based on longitudes and latitudes makes this model work poorly in global simulations. The problem with this grid is that the nodes are concentrated near the North and South Poles. Due to this characteristic, the Courant, Friedrich and Lewy-condition for numerical stability puts a sharp bound on the timestep length.